(a) Field of the Invention
The disclosure herein relates to a vehicle compressor control apparatus and a control method therefor, and more particularly to a vehicle compressor control apparatus for controlling a compressor operating rate based on a brake negative pressure margin rate. In addition, the disclosure provides methods for preventing the compressor from shutting down, which assists in preventing build-up of moisture on a wind shield.
(b) Description of the Related Art
In general, a vehicle may contain various devices for the convenience of the passengers. Example devices include an air conditioner for maintaining a comfortable internal temperature by suitably cooling the inside of the vehicle.
Traditional vehicle air conditioners use a coolant which is compressed and circulated through the rotating force of an engine. The air conditioner includes an evaporator, a compressor, a condenser, an expansion valve, and the like.
Gaseous coolant evaporated from the evaporator is introduced into the compressor and compressed, and the compressed, high temperature, high pressure gaseous coolant is sent to the condenser. The forcibly cooled coolant from the condenser passes through the expansion valve and expands to a wet steam state with low temperature and low pressure, and is then sent to the evaporator where the cooled coolant is gasified, and enters a low temperature, low pressure gaseous state.
Heat is transferred from air passing through the air conditioner to the coolant, thereby cooling the air flow. The cooled air is introduced into the inside of the vehicle to modulate the internal temperature of the vehicle.
The compressor compresses low pressure coolant gas into high pressure coolant gas which is then sent to the evaporator.
In a conventional vehicle air conditioner, if brake negative pressure is less than or equal to a predetermined negative pressure, the air conditioner compressor is deactivated in order to ensure brake performance. When the compressor is deactivated, under certain conditions, moisture may build up on the windshield, reducing visibility for the driver and increasing safety concerns.
In particular, because atmospheric pressure at higher elevations is lower than that in lower elevations, operating a vehicle at high elevations is disadvantageous when brake negative pressure reaches a level that causes the compressor to deactivate. Because the amount of time the compressor is deactivated increases as elevation increases, there is a corresponding increased risk of moisture build up and diminished visibility when at higher elevations.